Sole structures and articles of footwear having fluid-filled bladder elements

ABSTRACT

An article of footwear can include a midsole with a lower surface having a first recessed portion and an outsole coupled to the lower surface of the midsole, with the outsole having an upper surface with a second recessed portion. A first bladder element and a second bladder element can be provided in a stacked arrangement between the midsole and outsole, with an upper portion of the first bladder element that contacts the lower surface of the midsole and extends at least partially into the first recessed portion and a lower portion of the second bladder element that contacts the upper surface of the outsole and extends at least partially into the second recessed portion.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/799,596, filed Jan. 31, 2019. U.S. Provisional Application No.62/799,596 is incorporated herein by reference in its entirety.

FIELD

This disclosure is directed to cushioning systems in articles offootwear and, more particularly, to sole structures with fluid-filledbladder elements.

BACKGROUND

Articles of footwear can include cushioning systems to enhance theperformance of the article and/or the comfort of the wearer. Continuedimprovements in cushioning systems for articles of footwear aredesirable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral side view of a sole assembly having a cushioningsystem.

FIG. 2 is a top view of the sole assembly shown in FIG. 1.

FIG. 3 is a bottom view of the sole assembly shown in FIG. 1.

FIG. 4 is a perspective view of a pair of stacked bladder elements.

FIG. 5 is a front view of the stacked bladder elements shown in FIG. 4.

FIG. 6 is a side view of the stacked bladder elements shown in FIG. 4.

FIG. 7 is a top view of the stacked bladder elements shown in FIG. 4.

FIG. 8 is a bottom view of the stacked bladder elements shown in FIG. 4.

FIG. 9 is a cross-sectional view taken from FIG. 3.

FIG. 10 is a cross-sectional view taken from FIG. 3.

FIG. 11 is a side view of another embodiment of a sole assembly having acushioning system.

FIG. 12 is a side view of a midsole of an exemplary sole assembly.

FIG. 13 is a bottom view of the midsole shown in FIG. 12.

FIG. 14 is a bottom perspective view of the midsole shown in FIG. 12.

FIG. 15 is a side view of an outsole of an exemplary sole assembly.

FIG. 16 is a top view of the outsole shown in FIG. 15.

FIG. 17 is a top perspective view of the outsole shown in FIG. 15.

FIG. 18 is a side view of any article of footwear with a sole assemblyand an exemplary cushioning system.

FIG. 19 is an enlarged view of a portion of a heel region of the articleshown in FIG. 18.

FIG. 20 is a rear view of the article shown in FIG. 18.

FIG. 21 is a side view of a sole assembly of the article shown in FIG.18.

DETAILED DESCRIPTION

General Considerations

The systems and methods described herein, and individual componentsthereof, should not be construed as being limited to the particular usesor systems described herein in any way. Instead, this disclosure isdirected toward all novel and non-obvious features and aspects of thevarious disclosed embodiments, alone and in various combinations andsubcombinations with one another. For example, any features or aspectsof the disclosed embodiments can be used in various combinations andsubcombinations with one another, as will be recognized by an ordinarilyskilled artisan in the relevant field(s) in view of the informationdisclosed herein. In addition, the disclosed systems, methods, andcomponents thereof are not limited to any specific aspect or feature orcombinations thereof, nor do the disclosed things and methods requirethat any one or more specific advantages be present or problems besolved.

As used in this application the singular forms “a,” “an,” and “the”include the plural forms unless the context clearly dictates otherwise.Additionally, the term “includes” means “comprises.” Further, the term“coupled” or “secured” encompasses mechanical and chemical couplings, aswell as other practical ways of coupling or linking items together, anddoes not exclude the presence of intermediate elements between thecoupled items unless otherwise indicated, such as by referring toelements, or surfaces thereof, being “directly” coupled or secured.Furthermore, as used herein, the term “and/or” means any one item orcombination of items in the phrase.

As used herein, the term “exemplary” means serving as a non-limitingexample, instance, or illustration. As used herein, the terms “e.g.,”and “for example,” introduce a list of one or more non-limitingembodiments, examples, instances, and/or illustrations.

Although the operations of some of the disclosed methods are describedin a particular, sequential order for convenient presentation, it shouldbe understood that this manner of description encompasses rearrangement,unless a particular ordering is required by specific language set forthbelow. For example, operations described sequentially may in some casesbe rearranged or performed concurrently. Moreover, for the sake ofsimplicity, the attached figures may not show the various ways in whichthe disclosed things and methods can be used in conjunction with otherthings and methods. Additionally, the description sometimes uses termslike “provide,” “produce,” “determine,” and “select” to describe thedisclosed methods. These terms are high-level descriptions of the actualoperations that are performed. The actual operations that correspond tothese terms will vary depending on the particular implementation and arereadily discernible by one of ordinary skill in the art having thebenefit of this disclosure.

As used herein, the directional terms (e.g., “upper” and “lower”)generally correspond to the orientation of an article of footwear orsole assembly as it is configured to be worn by a wearer. For example,an “upwardly-facing surface” and/or an “upper surface” of a soleassembly refers to the surface oriented in the “superior” anatomicaldirection (i.e., toward the head of a wearer) when the article offootwear is being worn by the wearer. Similarly, the directional terms“downwardly” and/or “lower” refer to the anatomical direction “inferior”(i.e., toward the ground and away from the head of the wearer). “Front”means “anterior” (e.g., towards the toes), and “rear” means “posterior”(e.g., towards the heel). “Medial” means “toward the midline of thebody,” and “lateral” means “away from the midline of the body.”

Although the figures may illustrate an article of footwear intended foruse on only one foot (e.g., a right foot) of a wearer. One skilled inthe art will recognize that a corresponding article of footwear for theother foot (e.g., a left foot) would be a mirror image of the rightarticle of footwear.

Unless explained otherwise, all technical and scientific terms usedherein have the same meaning as commonly understood to one of ordinaryskill in the art to which this disclosure belongs. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present disclosure, suitable methods andmaterials are described below. The materials, methods, and examples areillustrative only and not intended to be limiting. Other features of thedisclosure are apparent from the detailed description, claims, abstract,and drawings.

The Disclosed Technology

Various sole structures and articles of footwear that include cushioningsystems, as well as methods of manufacturing the same, are disclosedherein.

In some embodiments, an article of footwear can include a midsole with alower surface having a first recessed portion and an outsole coupled tothe lower surface of the midsole, with the outsole having an uppersurface with a second recessed portion. The article of footwear caninclude a first bladder element and a second bladder element, eachhaving at least one chamber filled with a fluid (e.g., a gas). The firstbladder element can have an upper portion that contacts the lowersurface of the midsole and extends at least partially into the firstrecessed portion, and the second bladder element can have a lowerportion that contacts the upper surface of the outsole and extends atleast partially into the second recessed portion.

In some embodiments, the first bladder element can have a first internaldepression and the second bladder element a second internal depression,and the first recessed portion can include a first projection thatextends downward from the first recessed portion into the first internaldepression and the second recessed portion can include a secondprojection that extends upward from second recessed portion into thesecond internal depression.

In other embodiments, a window extends between a lateral side and amedial side of the article of footwear, and the window is collectivelydefined by at least a lower edge of the midsole and an upper edge of theoutsole. A first exposed portion of the first bladder element and asecond exposed portion of the second bladder element can be visible froma lateral and/or medial side of the window, with a first unexposedportion of the first bladder element and a second unexposed portion ofthe second bladder element being not exposed (e.g., covered by themidsole or outsole, respectively).

In some embodiments, the window can be in a heel region of the articleof footwear. In other embodiments, a first peripheral bond of the firstbladder element and a second peripheral bond of the second bladderelement are in the unexposed portions (e.g., covered by the midsole oroutsole, respectively). In some embodiments, the first internaldepression can be formed from a first internal weld area of the firstbladder element and the second internal depression can be formed from asecond internal weld area of the second bladder element.

The outsole can extend along an entire length of the article offootwear, or form only a portion of a ground-contacting surface of thearticle of footwear. For example, the outsole can extend across the heelregion of the article of footwear. In some embodiments, the outsole canhave a notched portion that engages with the midsole and/or a portion ofa second outsole member.

The upper portion of the first bladder element can be secured to thelower surface of the midsole and the lower portion of the second bladderelement can be secured to the upper surface of the outsole. Similarly, alower surface of the first bladder element can be secured (e.g.,adhered) to an upper surface of the second bladder element. In someembodiments, the first and second exposed portions are spaced apart froma heel side of the window and from a forefoot side of the window and aheel-side aperture is defined between the heel side of the window andthe first and second exposed portions and a forefoot-side aperture isdefined between the forefoot side of the window and the first and secondexposed portions. An upper can be secured to the midsole and/or outsole.

In some embodiments, a sole structure comprises a midsole and outsole asdescribed above and the sole structure can be secured to an upper toform an article of footwear.

In another embodiment, a method of manufacturing an article of footwearis provided. The method includes forming a midsole with a first recessedportion in a lower surface of the midsole and a first projectionextending from the first recessed portion, forming an outsole with asecond recessed portion in an upper surface of the outsole and a secondprojection extending from the second recessed portion, positioning anupper portion of a first bladder element in contact with the lowersurface of the midsole with the first bladder element extending at leastpartially into the first recessed portion and with the first projectionbeing received in a first depression in an internal area of the firstbladder element, positioning a lower portion of a second bladder elementin contact with the upper surface of the outsole with the second bladderelement extending at least partially into the second recessed portionand with the second projection being received in a second depression inan internal area of the second bladder element, and securing an uppersurface of the outsole to a lower surface of the midsole.

In some embodiments, the method can also include securing the upperportion of the first bladder element to the lower surface of the midsoleand securing the lower portion of the second bladder element to theupper surface of the outsole. A lower surface of the first bladderelement can also be secured to an upper surface of the second bladderelement (e.g., with an adhesive).

In some embodiments, the act of securing the upper surface of theoutsole to the lower surface of the midsole forms a window that extendsbetween a lateral side and a medial side of the article of footwear, thewindow being collectively defined by at least a lower edge of themidsole and an upper edge of the outsole. The act of positioning thefirst bladder element can include exposing a first exposed portion ofthe first bladder through the window and covering first unexposedportion of the first bladder element so that it is not exposed (e.g.,the first unexposed portion can be covered by the midsole), and the actof positioning the second bladder element can include exposing a secondexposed portion of the second bladder element through the window andcovering a second unexposed portion of the second bladder element sothat it is not exposed (e.g., the second unexposed portion can becovered by the sole). The first and second unexposed portions caninclude portions of the first and second bladder elements, respectively,where a peripheral bond is located.

In some embodiments, the first and second recessed portions can beformed in a heel region of the article of footwear. A first internaldepression can be formed from a first internal weld area of the firstbladder element and a second internal depression can be formed from asecond internal weld area of the second bladder element.

The outsole can extend along an entire length of the article of footwearor the outsole can form forms only a portion of a ground-contactingsurface of the article of footwear such that securing the upper surfaceof the outsole to the lower surface of the midsole covers only a portionof the lower surface of the midsole. If the outsole forms only a portionof the ground-contacting surface, the outsole can be a first outsolemember in a heel region of the article of footwear, and the method caninclude securing a second outsole member to the article of footwear. Anupper can be secured to the midsole and/or outsole, which collectivelycan be considered a sole structure or sole assembly.

Exemplary Embodiments of Sole Assemblies and Articles of Footwear

Articles of footwear (also referred to herein as “articles”) can includerunning shoes, soccer shoes, football shoes, rugby shoes, basketballshoes, baseball shoes, tennis shoes, sneakers, boots, sandals, dressshoes, work shoes, and any other type of footwear to which thecushioning systems disclosed herein may be applied. Articles of footweartypically include a sole structure, also referred to as a sole assemblyherein, and an upper coupled to the sole structure. The upper forms aninterior void configured to receive a foot of a wearer.

FIGS. 1-3 illustrate a sole assembly 10 for use with an article offootwear. Sole assembly 10 include a midsole 12 and an outsole 14. Abladder system 16 is positioned between midsole 12 and outsole 14.

Portions of the sole assembly (and the corresponding article offootwear) may be identified based on regions of the foot located at ornear that portion of the article of footwear when the footwear is wornon the properly sized foot. For example, as shown in FIG. 1, an articleof footwear and/or a sole assembly may be considered as having a heelregion 18 at the rear of the foot, a midfoot region 20 at the middle orarch area of the foot, and a forefoot region 22 at the front of thefoot. Footwear and/or sole assemblies also include a lateral side 24(the “outside” or “little toe side” of the foot) and a medial side 26(the “inside” or “big toe side” of the foot). The lateral and medialsides of the footwear extend through the forefoot, midfoot, and heelregions and generally correspond with opposite sides of the footwear(and may be considered as being separated by a central longitudinal axisLA).

Midsole 12 can be formed of any suitable material. For example, midsole12 can be formed from a resilient, polymer foam material, such aspolyurethane foam or ethylvinylacetate (“EVA”) foam, that extendsthroughout the length of the article of footwear. The properties of thepolymer foam material in the midsole are primarily dependent uponfactors that include the dimensional configuration of the midsole andthe specific characteristics of the material selected for the polymerfoam, including the density of the polymer foam material. By varyingthese factors throughout the midsole, the relative stiffness and degreeof ground reaction force attenuation may be altered to meet the specificdemands of the activity for which the footwear is intended to be used.The top surface 28 of the midsole 12 can be contoured, e.g., tocomfortably support and/or help position a plantar surface of a wearer'sfoot. As discussed in more detail herein, midsole 12 can be attached toan upper.

Outsole 14 is a ground-contacting member and that can be formed, forexample, of a durable, wear resistant material that includes texturingor other features to improve traction. For example, outsole 14 can beformed of rubber, phylon, phyllite, thermoplastic polyurethane, andother suitable materials.

As shown in FIG. 1, outsole 14 can be secured to a bottom surface 30 ofmidsole 12. For example, a top surface 32 of outsole 14 can engage withthe bottom surface 30 of midsole 12, and the two surfaces can be securedtogether, such as with an adhesive.

FIGS. 4-8 illustrate a bladder system 16 that comprises a pair offluid-filled bladder elements 34, 36 that are stacked with bladderelement 34 on top of bladder element 36. Each of the bladder elementsdefines a respective sealable internal cavity 38, 40. Bladder elements34, 36 can be formed with at least one upper recessed portion 42 and atleast one lower recessed portion 44. The at least one upper recessedportion 42 and at least one lower recessed portion 44 are surrounded,respectively, by an upper peripheral surface 46 and a lower peripheralsurface 48 that extend above recessed portions 42 and below recessedportion 44, respectively. Thus, the recessed portions 42, 44 (alsoreferred to herein as depressions) of the bladder elements includesurfaces that are spaced apart from a peripheral surface and which arelower in height than the upper peripheral surface or higher in heightthan the lower peripheral surface.

As shown in FIG. 4, upper and lower peripheral surfaces 46, 48 extendentirely around a periphery of bladder elements 34, 36 to completelyenclose upper and lower recessed portions 42, 44. However, in someembodiments, peripheral surfaces 46, 48 can only partially surround theupper and/or lower recessed portions (e.g., such as by forming ahorseshoe shape with one side of the upper and/or lower recessedportions not surrounded by the upper and/or lower peripheral surface).

Referring again to FIG. 1, midsole 12 and outsole 14 are shaped tocollectively define a window 50 (e.g., a gap or cutout) through soleassembly 10. Window 50 extends from the lateral side 24 to the medialside 26 in the heel region 18 of sole assembly 10. Bladder system 16 isreceived between midsole 12 and outsole 14 so that only a portion ofeach of bladder elements 34, 36 are visible from the medial and lateralsides of the sole assembly.

For example, as shown in FIG. 1, each of the bladder elements 34, 36 hasan exposed portion and an unexposed portion. The unexposed portion offirst bladder element 34 includes an upper portion that is not visiblethrough window 50 (e.g., as shown in dashed lines). The unexposedportion includes the area of first bladder element 34 where a peripheralbond 60 (discussed below) is located. Similarly, the unexposed portionof second bladder element 36 includes a lower portion that is notvisible through window 50 (e.g., as shown in dashed lines), whichincludes an area of second bladder element 36 where its peripheral bond60 is located.

When viewed from the lateral or medial side, as shown in FIGS. 1 and 6,adjacent peripheral surfaces of the stacked bladder elements 34, 36(i.e., lower peripheral surface 48 of bladder element 34 and upperperipheral surface 46 of bladder element 36) contact each other alongtheir lateral and medial side surfaces.

In some embodiments, as shown in FIG. 1, window 50 can be sized so thatbladder elements 34, 36 do not extend the entire length of window 50.For example, FIG. 1 illustrates a rear gap 52 and a front gap 54 on therear and front sides, respectively, of bladder elements 34, 36. Rear gap52 and front gap 54 can provide unobstructed views though window 50 fromthe medial side to the lateral side, and vice versa.

Bladder elements 34, 36 can be formed in various manners. For example,each bladder element can be formed by securing a first polymeric sheet56 to a second polymeric sheet 58 to define the respective internalcavity 38, 40. First and second polymeric sheets 56, 58 aresubstantially impermeable to the fluid to be contained within cavities38, 40. First polymeric sheet 56 and second polymeric sheet 58 can becoupled together (e.g., welded) around their respective peripheries toform a peripheral bond 60.

As shown in FIG. 5, first polymeric sheet 56 forms the upper peripheralsurface 46 and a portion of a sidewall 62 of bladder element 34, andsecond polymeric sheet 58 forms the lower peripheral surface 48 andanother portion of sidewall 62 of bladder element 34. Peripheral bond 60can be located at a midpoint of sidewall 62 or, alternately, positionedcloser to the lower peripheral surface 48 or the upper peripheralsurface 46.

Bladder elements can be thermoformed in a mold assembly, with the firstand second polymeric sheets 56, 58 being vacuum formed to the shape ofthe mold assembly during the thermoforming process. The sheets can bebonded to one another to form the peripheral bond by compression duringthe thermoforming process and fluid can be provided to the internalcavity of the bladder element through a fill tube. After inflation ofthe bladder element, the fill tube can be plugged and subsequentlytrimmed prior to assembling the sole assembly or article of footwear. Asused herein, a “fluid” includes a gas, including air, an inert gas suchas nitrogen, or another gas.

In addition to the peripheral bond 60, first and second polymeric sheets56, 58 can be welded together at one or more internal areas to achieve adesired shape and configuration of the bladder element. For example, asshown in FIGS. 7 and 8, upper and lower recessed portions 42, 44 can beformed by bonding the first and second polymeric sheets 56, 58 togetherat an interior bond region 64 (e.g., internal weld area) that is spacedaway from the peripheral surfaces 46, 48. When an interior bond regionis formed on both sides of the bladder element, as shown in FIGS. 7 and8, for example, the terms interior bond region and interior weld arearefer to regions on either the top or bottom of a bladder element.

As shown in FIGS. 9 and 10, midsole 12 and outsole 14 can be sized toreceive a respective bladder element 34, 36. For example, midsole 12 cancomprise a peripheral recessed portion 66 and raised surface, such asone or more projections 68 extending downward relative to recessedportion 66. Outsole 14 can likewise comprise a peripheral recessedportion 70 and a central raised surface, such as one or more projections72 extending upward relative to recessed portion 70. Peripheral recessedportion 66 is sized to engage with upper peripheral surface 46 ofbladder element 34 and projection 68 is sized to engage with upperrecessed portion 42. Similarly, peripheral recessed portion 70 is sizedto engage with lower peripheral surface 48 of bladder element 34 andprojection 72 is sized to engage with lower recessed portion 44.

By providing mating surfaces in this manner (e.g., projections extendinginto recessed portions of the bladder elements and peripheral surfacesof the bladder elements into recessed portions of the midsole/sole), thebladder elements can be better secured in a desired position. Inaddition to a friction fit between the bladder elements and adjacentsurfaces of the midsole and outsole, adhesives can be provided tofurther secure these elements in position relative to each other. Also,because of the non-linear shapes of the adjacent surfaces describedabove, in some embodiments, a greater amount of surface area may beavailable for applying adhesives.

Referring again to FIG. 1, the recessed portions of the midsole andoutsole are preferably sized to accommodate the peripheral bonds ofrespective bladder elements entirely within the respective midsole oroutsole region, such that the peripheral bond is not exposed by window50. For example, peripheral bond 60 of bladder element 34 is receivedwithin the midsole 12 (i.e., an internal surface of midsole 12 contactsand/or covers peripheral bond 60) so that it is not exposed by window50, and peripheral bond 60 of bladder element 36 is received within theoutsole 14 (i.e., an internal surface of outsole 14 contacts and/orcovers peripheral bond 60) so that it is not exposed by window 50.Receiving the peripheral bonds 60 of the bladder elements within themidsole and outsole elements as shown in FIG. 1, can improve both thefunction and aesthetics of the article of footwear. For example, exposedperipheral bonds may be more susceptible to failing by undesired contactwith external elements as well as less desirable to view through window50.

FIG. 1 illustrates outsole 14 as a “cap” that covers only the heelregion 18 with the midsole 12 directly contacting the ground in themidfoot region 20 and forefoot region 22. Alternatively, outsole 14 canextend the entire length of the bottom of sole assembly 10 as shown inFIG. 11. In particular, FIG. 11 illustrates a second outsole member 74.Second outsole member 74 can be integrally formed with outsole 14, withboth collectively forming an outsole structure joined to midsole 12. Inother embodiments, second outsole member 74 can be separate from outsole14 and secured to the midsole 12 separately from outsole 14—eitherbefore, after, or during the securing of outsole 14 to midsole 12.Second outsole member 74 can extend the length of sole assembly 10 or itcan only in a midfoot 20 or forefoot region 22 (e.g., extending from aforward portion of outsole 14 to the toe side of sole assembly 10).

FIGS. 12-17 illustrate features of midsole 12 and outsole 14 and themanner in which they are shaped to receive the bladder elementsdescribed herein. FIG. 12 is a side view, FIG. 13 is a bottom view, andFIG. 14 is a bottom perspective view of an exemplary midsole 12. Midsole12 defines a portion of window 50 by the shape of its cutout in the heelregion. As shown in FIGS. 13 and 14, peripheral recessed portion 66surrounds a raised surface, projection 68, that extends downwardrelative to recessed portion 66. Projection 68 is sized to be receivedwithin upper recessed portion 42 of bladder element 34. Thus, the shapeof projection 68 can vary depending on the shape of upper recessedportion 42. For example, the exemplary projection of FIG. 14 is taperedtowards the end to better accommodate the bladder element 34 shown inFIG. 4. In addition, projection 68 of the illustrated embodiment is ovalshaped to correspond to the oval-shaped upper recessed portion 42 ofbladder element 34. Different shapes and different numbers ofprojections are possible depending on the shape of the bladder elementthat is to be received in midsole 12.

FIG. 15-17 illustrate an exemplary outsole 14 that can be secured tomidsole 12, with the bladder system 16 positioned therebetween. FIG. 15is a side view, FIG. 16 is a top view, and FIG. 17 is a top perspectiveview of outsole 14. As shown in FIGS. 16 and 17, a peripheral recessedportion 70 surrounds a central raised surface, projection 72, thatextends upward relative to recessed portion 70. In the same manner asdescribed above in connection with projection 68 and FIGS. 12-14,projection 72 is sized to be received within lower recessed portion 44of bladder element 36. Thus, the shape of projection 72 can likewisevary depending on the shape of lower recessed portion 44.

The shape of outsole 14 can vary to provide a more secure attachmentbetween outsole 14 and midsole 12. For example, as shown in FIG. 16,outsole 14 has a notched portion 76 that is sized to be received in acorresponding mating portion 78 of midsole 12 to provide a more securefit between the midsole and outsole when the two are coupled together(e.g., with adhesives).

FIG. 18 illustrates an exemplary embodiment of an article of footwearhaving a sole assembly as described herein. As shown in FIG. 18, anupper 80 is secured to a sole assembly that includes midsole 12 andoutsole 14. A bladder system, including bladder elements 34, 36, issecured within window 50 as described herein. As shown in FIGS. 18-21,outsole 14 can comprise a notched portion 82 which engages withcorresponding portion 84 of midsole 12 to provide for a more securecoupling between the midsole and outsole.

It should be understood that the structure of bladder elements describedherein can vary. For example, instead of a single fluid-filled chamber,the bladder elements can have multiple, discrete fluid-filled chambers.Such discrete fluid-filled chambers can be inflated at differentpressures to create softer or stiffer areas of cushioning. In addition,as discussed above, more than one internal welds can be provided. Forexample, instead of a single weld area 64, two or more smallerspaced-apart weld areas can be formed with an intermediate fluid-filledregion (either as a part of the main chamber of the bladder element oras a separate discrete chamber). If more than one weld areas areprovided, a corresponding change can be made in the number ofprojections provided, as well as a corresponding change in theirposition and structure. Thus, for example, if the bladder element hastwo circular internal weld areas instead of a single oval-shaped weldarea, two circular projections could be provided instead of a singleoval-shaped projection.

In addition to the peripheral bond and one or more internal welds, theshape and characteristics of the bladder elements can be controlled byproviding other structures within the bladder element such as tensilemembers. Additional details about the use of tensile members and/orother internal welds can be found in U.S. Pat. Nos. 5,083,361,6,385,864, 6,571,490, and 7,386,946, each of which is entirelyincorporated herein by reference.

Bladder elements 34, 36 can also be formed of different colors and/orwith different transparencies. For example, in some embodiments, thebladder elements can be substantially transparent. As used herein, abladder element is “substantially transparent” if it has a luminoustransmittance (i.e., a percentage of incident light that is transmitted)of at least 80 percent and haze (i.e., percentage of transmitted lightthat is scattered) of not more than 56 percent.

The various materials used for bladder elements 34, 36, and otherembodiments of bladder elements discussed herein, may be substantiallytransparent. Those skilled in the art will readily understand a varietyof methods to determine luminous transmittance and haze of an object,such as a bladder element. For example, the luminous transmittance andhaze of the bladder element can be determined according to AmericanSociety for Testing and Materials (ASTM) Standard D1003-00, StandardTest Method for Haze and Luminous Transmittance of Transparent Plastics.Additionally, in some embodiments, the bladder elements may have atinted color.

Although bladder elements 34, 36 are shown positioned in a heel regionof the article of footwear, bladder element 34, 36 may instead or inaddition be positioned in the midfoot region or the forefoot region.

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples of the invention andshould not be taken as limiting the scope of the invention. Rather, thescope of the invention is defined by the following claims. I thereforeclaim as my invention all that comes within the scope and spirit ofthese claims.

I claim:
 1. An article of footwear comprising: a midsole having a lowersurface with a first recessed portion; an outsole coupled to the lowersurface of the midsole, the outsole having an upper surface with asecond recessed portion; a first bladder element having at least onechamber filled with a fluid, the first bladder element having an upperportion contacting the lower surface of the midsole and extending atleast partially into the first recessed portion; and a second bladderelement having at least one chamber filled with a fluid, the secondbladder element having a lower portion contacting the upper surface ofthe outsole and extending at least partially into the second recessedportion, wherein the first bladder element has a first internaldepression and the second bladder element has a second internaldepression, and wherein the first recessed portion comprises a firstprojection that extends downward from the first recessed portion intothe first internal depression and the second recessed portion comprisesa second projection that extends upward from second recessed portioninto the second internal depression.
 2. The article of footwear of claim1, further comprising: a window extending between a lateral side and amedial side of the article of footwear, the window being collectivelydefined by at least a lower edge of the midsole and an upper edge of theoutsole; a first exposed portion of the first bladder element that isexposed by the window and a first unexposed portion of the first bladderelement that is not exposed through the window; and a second exposedportion of the second bladder element that is exposed by the window anda second unexposed portion of the second bladder element that is notexposed through the window.
 3. The article of footwear of claim 2,wherein the window is in a heel region of the article of footwear. 4.The article of footwear of claim 2, wherein the first unexposed portionincludes a first peripheral bond of the first bladder element and thesecond unexposed portion includes a second peripheral bond of the secondbladder element.
 5. The article of footwear of claim 1, wherein thefirst internal depression is formed from a first internal weld area ofthe first bladder element and the second internal depression is formedfrom a second internal weld area of the second bladder element.
 6. Thearticle of footwear of claim 1, wherein the outsole extends along anentire length of the article of footwear.
 7. The article of footwear ofclaim 1, wherein the outsole forms only a portion of a ground-contactingsurface of the article of footwear.
 8. The article of footwear of claim7, wherein the outsole extends across a heel region of the article offootwear.
 9. The article of footwear of claim 7, wherein the outsolecomprises a notched portion that engages with the midsole.
 10. Thearticle of footwear of claim 7, wherein the outsole is a first outsolemember in a heel region of the article of footwear, and the firstoutsole member has a notched portion that engages with a mating portionof a second outsole member.
 11. The article of footwear of claim 10,wherein the upper portion of the first bladder element is secured to thelower surface of the midsole and the lower portion of the second bladderelement is secured to the upper surface of the outsole.
 12. The articleof footwear of claim 1, wherein a lower surface of the first bladderelement is adhered to an upper surface of the second bladder element.13. The article of footwear of claim 2, wherein the first and secondexposed portions are spaced apart from a heel side of the window andfrom a forefoot side of the window, and a heel-side aperture is definedbetween the heel side of the window and the first and second exposedportions, and a forefoot-side aperture is defined between the forefootside of the window and the first and second exposed portions.
 14. Thearticle of footwear of claim 1, further comprising an upper secured tothe midsole and/or the outsole.
 15. A method of manufacturing an articleof footwear comprising: forming a midsole with a first recessed portionin a lower surface of the midsole and a first projection extending fromthe first recessed portion; forming an outsole with a second recessedportion in an upper surface of the outsole and a second projectionextending from the second recessed portion; positioning an upper portionof a first bladder element in contact with the lower surface of themidsole with the first bladder element extending at least partially intothe first recessed portion and with the first projection being receivedin a first depression in an internal area of the first bladder element;positioning a lower portion of a second bladder element in contact withthe upper surface of the outsole with the second bladder elementextending at least partially into the second recessed portion and withthe second projection being received in a second depression in aninternal area of the second bladder element; and securing an uppersurface of the outsole to a lower surface of the midsole.
 16. The methodof claim 15, further comprising: securing the upper portion of the firstbladder element to the lower surface of the midsole; and securing thelower portion of the second bladder element to the upper surface of theoutsole.
 17. The method of claim 15, further comprising securing a lowersurface of the first bladder element to an upper surface of the secondbladder element with an adhesive.
 18. The method of claim 15, whereinsecuring the upper surface of the outsole to the lower surface of themidsole forms a window that extends between a lateral side and a medialside of the article of footwear, the window being collectively definedby at least a lower edge of the midsole and an upper edge of theoutsole.
 19. The method of claim 18, further comprising: positioning thefirst bladder element so that a first exposed portion of the firstbladder element is exposed by the window and a first unexposed portionof the first bladder element is not exposed through the window; andpositioning the second bladder element so that a second exposed portionof the second bladder element is exposed by the window and a secondunexposed portion of the second bladder element is not exposed throughthe window.
 20. The method of claim 19, wherein positioning the firstbladder element comprises positioning a first peripheral bond of thefirst bladder element so that the first peripheral bond is in the firstunexposed portion, and wherein positioning the second bladder elementcomprises positioning a second peripheral bond of the second bladderelement so that the second peripheral bond is in the second unexposedportion.